Theoretical Study of the Physisorption of CO on Metal Oxide Surfaces Using the KSCED-DFT Approach

1998 ◽  
Vol 63 (9) ◽  
pp. 1447-1459 ◽  
Author(s):  
Nathalie Vulliermet ◽  
Tomasz A. Wesolowski ◽  
Jacques Weber
Keyword(s):  
Metal Oxide ◽  
Frequency Shift ◽  
Electron Density ◽  
Effective Potential ◽  
Theoretical Study ◽  
Adsorbed Molecule ◽  
Theoretical Studies ◽  
Metal Oxide Surfaces ◽  
Stretching Vibration ◽  
Good Agreement

Theoretical studies on structure and stretching frequency of the CO molecule physisorbed on the MgO(100) or ZnO(1010) surfaces are reported. The properties of the adsorbed molecule were investigated by means of the recently developed formalism of Kohn-Sham equations with constrained electron density (KSCED). The KSCED method makes it possible to divide a large system into two subsystems and to study one of them using Kohn-Sham-like equations with an effective potential which takes into account the interactions between subsystems. This method (KSCED) was shown to be adequate to study the properties of the CO molecule adsorbed on the MgO(100) surface as reported in a previous paper (Wesolowski et. al.: J. Mol. Struct., THEOCHEM, in press). The effect of the interactions with the surface on the CO stretching frequency and geometry was analyzed for vertically bound (C-down) CO at the Zn-site of the ZnO(1010) surface. The ZnO(1010) surface was represented using several cluster models: Zn2+, (ZnO3)4-, or Zn9O9 embedded in a matrix of point charges. The KSCED frequency shift of the CO stretching vibration is blue-shifted and in good agreement with experiment.

scholarly journals Theoretical Studies of Structure, Spectroscopy, and Properties of a New Hydrazine Derivative

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Hajar Sahebalzamani ◽  
Farshid Salimi ◽  
Elmira Dornapour
Keyword(s):  
Ground State ◽  
Theoretical Study ◽  
Molecular Geometry ◽  
Vibrational Frequencies ◽  
Basis Sets ◽  
Theoretical Studies ◽  
Hydrazine Derivative ◽  
Homo And Lumo ◽  
Good Agreement ◽  
Ft Raman

We will report a combined experimental and theoretical study on molecular structure, vibrational spectra, and energies of (E)-1-(2,4-dinitrophenyl)-2-[(4-methylphenyl)methylidene]hydrazine (1). The molecular geometry and vibrational frequencies and energies in the ground state are calculated by using HF and DFT levels of theory with 6-311G basis sets. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. The harmonic vibrational frequencies were calculated, and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar-type spectrograms.

Theoretical Study of Pyrrole Interaction with Alkali Metal Exchanged Zeolites: Investigation of the Reliability of Cluster and Periodic Models

2003 ◽  
Vol 68 (10) ◽  
pp. 1848-1860 ◽  
Author(s):  
Jan Kučera ◽  
Petr Nachtigall
Keyword(s):  
Alkali Metal ◽  
Theoretical Study ◽  
Interatomic Potential ◽  
Alkali Metal Cation ◽  
Cluster Models ◽  
Zeolite Framework ◽  
Stretching Vibration ◽  
Periodic Models ◽  
Experimental Shift ◽  
Good Agreement

The interaction of pyrrole with the alkali metal exchanged zeolites was investigated using cluster models of various sizes and with a hybrid quantum mechanics/interatomic potential function model (QM-pot). The interaction of pyrrole with the M+/zeolite is dominantly driven by the interaction of pyrrole π-system with the alkali metal cation. Further stabilization is due to the formation of the hydrogen bonds between NH and framework oxygen atoms. A good agreement between calculated and experimental shift of the N-H stretching vibration upon the adsorption of pyrrole in M+/zeolite was found with the periodic QM-pot model. The performance of the cluster models for the description of pyrrole interaction with M+/zeolite is discussed. Reliable results can be obtained only when large cluster models are used for description of the zeolite framework.

Theoretical study of H bonds of HArF and HF with isoelectronic systems N2, CO, and BF

2010 ◽  
Vol 88 (4) ◽  
pp. 352-361
Author(s):  
An Yong Li ◽  
Li Juan Cao ◽  
Hong Bo Ji
Keyword(s):  
Frequency Shift ◽  
Bond Length ◽  
Electron Density ◽  
Electrostatic Interaction ◽  
Theoretical Study ◽  
Blue Shift ◽  
Length Change ◽  
Red Shift ◽  
P Value ◽  
Small Contribution

The H bonds of HArF and HF with N2, CO, and BF were studied at the MP2(full)/6-311++G(2d, 2p) level. The results show that only the complexes WY···HArF (WY = N2, OC) and WY···HF (WY = N2, OC, FB) are stable, the H-bonding WY···HArF leads to contraction of the HAr bond with a concomitant frequency blue shift, but the H-bonding WY···HF causes the HF bond to elongate with a frequency red shift. A quantity P is defined to measure polarization of the HX bond; the H bonding causes the P value of the HX bond (X = Ar, F) to increase. The HX bond length change and frequency shift in the H-bonding WY···HArF and WY···HF are mainly caused by intermolecular hyperconjugation, n(Y) → σ*(HX) (X = Ar, F), where electrostatic interaction has only a small contribution. In HArF, the strong intramolecular hyperconjugation, n(F) → σ*(HAr), can adjust electron density on σ*(HAr); upon formation of H bonding, the HAr stretching frequency blue shift is caused by a decrease of intramolecular hyperconjugation and an increase of the s character of the Ar hybrid in the HAr bond, induced by the intermolecular hyperconjugation. In the H bonds of HF without intramolecular hyperconjugation, the intermolecular hyperconjugation, n(Y) → σ*(HF), leads to a red shift of the HF bond, although there is also large rehybridization.

Partition Coefficients of Methylated DNA Bases Obtained from Free Energy Calculations with Molecular Electron Density Derived Atomic Charges.

2018 ◽  
Author(s):  
Alejandro Lara ◽  
Maximiliano Riquelme ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Electron Density ◽  
Partition Coefficients ◽  
Dna Bases ◽  
Atomic Charges ◽  
Free Energies ◽  
Solvation Model ◽  
Minimal Basis ◽  
Methylated Dna ◽  
Implicit Solvation Model ◽  
Good Agreement

<div> <div> <div> <p>Partition coefficients serve in various areas as pharmacology and environmental sciences to predict the hydrophobicity of different substances. Recently, they have been also used to address the accuracy of force fields for various organic compounds and specifically the methylated DNA bases. In this study atomic charges were derived by different partitioning methods (Hirshfeld and Minimal Basis Iterative Stockholder) directly from the electron density obtained by electronic structure calculations in vac- uum, with an implicit solvation model or with explicit solvation taking the dynamics of the solute and the solvent into account. To test the ability of these charges to describe electrostatic interactions in force fields for condensed phases the original atomic charges of the AMBER99 force field were replaced with the new atomic charges and combined with different solvent models to obtain the hydration and chloroform solvation free energies by molecular dynamics simulations. Chloroform-water partition coefficients derived from the obtained free energies were compared to experimental and previously reported values obtained with the GAFF or the AMBER-99 force field. The results show that good agreement with experimental data is obtained when the polarization of the electron density by the solvent has been taken into account deriving the atomic charges of polar DNA bases and when the energy needed to polarize the electron den- sity of the solute has been considered in the transfer free energy. These results were further confirmed by hydration free energies of polar and aromatic amino acid side chain analogues. Comparison of the two partitioning methods Hirsheld-I and Minimal Basis Iterative Stockholder (MBIS) revealed some deficiencies in the Hirshfeld-I method related to nonexistent isolated anionic nitrogen pro-atoms used in the method. Hydration free energies and partitioning coefficients obtained with atomic charges from the MBIS partitioning method accounting for polarization by the implicit solvation model are in good agreement with the experimental values. </p> </div> </div> </div>

scholarly journals Conversion of Methanol on Rutile TiO2 (110) and Tungsten Oxide Clusters: 2. The Role of Defects and Electron Transfer in Bifunctional Oxidic Photocatalysts

2021 ◽  
Author(s):  
Lars Mohrhusen ◽  
Jessica Kräuter ◽  
Katharina Al-Shamery
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Metal Oxide ◽  
Tungsten Oxide ◽  
Organic Compounds ◽  
Uv Irradiation ◽  
Organic P ◽  
Rutile Tio2 ◽  
Metal Oxide Surfaces

The photochemical conversion of organic compounds on tailored transition metal oxide surfaces by (UV) irradiation has found wide applications ranging from the production of chemicals to the degradation of organic...

scholarly journals Aqueous Solvation Dynamics at Metal Oxide Surfaces

2006 ◽  
Vol 110 (15) ◽  
pp. 7835-7844 ◽  
Author(s):  
Erwin Portuondo-Campa ◽  
Andreas Tortschanoff ◽  
Frank van Mourik ◽  
Jacques-Edouard Moser ◽  
Andreas Kornherr ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Oxide Surfaces ◽  
Solvation Dynamics ◽  
Metal Oxide Surfaces ◽  
Aqueous Solvation

Explanation of the Influence of Inflow Air Content on the Lift of Cavitating Hydrofoils

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Lift Coefficient ◽  
Cavity Surface ◽  
Air Bubbles ◽  
Incoming Flow ◽  
Fluid Density ◽  
Air Content ◽  
Theoretical Results ◽  
Good Agreement

According to several known experiments, an increase of the incoming flow air content can increase the hydrofoil lift coefficient. The presented theoretical study shows that such increase is associated with the decrease of the fluid density at the cavity surface. This decrease is caused by entrainment of air bubbles to the cavity from the surrounding flow. The theoretical results based on such explanation are in a good agreement with the earlier published experimental data for NACA0015.

scholarly journals Investigation of Water Adsorption on Metal Oxide Surfaces under Conditions Representative of PuO2 Storage Containers

2013 ◽  
Vol 53 (21) ◽  
pp. 81-94 ◽  
Author(s):  
P. M. Murphy ◽  
C. Boxall ◽  
R. J. Taylor ◽  
D. A. Woodhead
Keyword(s):  
Metal Oxide ◽  
Water Adsorption ◽  
Oxide Surfaces ◽  
Metal Oxide Surfaces ◽  
Storage Containers
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